Infrared Study of the Molecular Orientation in Ultrathin Films of Behenic Acid Methyl Ester: Comparison between Single Langmuir−Blodgett Monolayers and Spin-Coated Multilayers
Bibliographic record
Abstract
Single Langmuir−Blodgett (LB) monolayers of behenic acid methyl ester (BAME) were studied by infrared spectroscopy. Anisotropic optical constants of this system were calculated from a perpendicular-polarized attenuated total reflectance spectrum and a parallel-polarized reflection−absorption spectrum and were compared to those obtained, in a previous article, for spin-coated multilayers (Pelletier, I.; Bourque, H.; Buffeteau, T.; Blaudez, D.; Desbat, B.; Pézolet, M. J. Phys. Chem. B 2002, 106, 1968). These optical constants were used to calculate the tilt angle of the alkyl chains in both types of films deposited on solid substrates and to simulate polarization modulation reflection−absorption spectra of the Langmuir film at the air/water interface. The results indicate that the molecular tilt angle is near 30° for spin-coated multilayers, while single LB monolayers have a tilt angle of 11 ± 2°. A similar orientation of the alkyl chains is obtained on single monolayers deposited onto solid substrates or spread at the air/water interface (Langmuir films), showing that no change of molecular orientation results from the Langmuir−Blodgett transfer. The presence in the infrared spectra of several bands due to the methylene wagging and twisting modes and of the splitting of the band due to the methylene bending mode at 1463 and 1473 cm - 1 indicates that in all types of films BAME alkyl chains are in the all-trans conformation and packed in an orthorhombic subcell. However, under certain circumstances, the splitting of the methylene bending mode band was not observed. This phenomenon is associated with the roughness of the solid substrates supporting the LB film leading to the formation of gauche defects in the film and thus to a molecular disordering of the monolayer.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".